Help! Complex hit and run?

I went to a job interview for a Federal agency. After I returned to my car from the interview, The entire drivers side of my car was smashed in ($5000+ in damage) and a note was left by the security guards to contact them. I contacted them and they indicated that my car was hit by an employee who drove off and there are two witnesses and that they also have video of the incident and know the identity of the employee who hit my car and drove off. Long story short I called the local police (since this parking lot technically was public property and security wasn't too interested in doing anything about this ) and the police asked the security guards (who are rental cops with no power to arrest someone) if they can see the video and speak with the witnesses. The police explained to me that they do have jurisdiction for this particular parking lot and would assist me. The security guards refused to give the names of the witnesses to police and told the police that they are viewing the video tape and will contact federal authorities to take actions against this employee and will get with the police when they get finished examining the video tape. The police told the guards they would be more than happy to look at the video tape but the security guards refused to give them the tape. Can these security guards refuse to give the police a video tape and the identities of the people who witnessed this person hit my car and drive off? The police told me that since the guards weren't cooperating, there really isn't much they can do other than issue a subpena and force them to turn over the video tape and the identities of the witnesses but it's possible the agency can successfully fight to the subpena so it really isn't worth the time. I really want this driver to face consequences for his/her actions and I'm quite sure my insurance rates will go up because this person hit me and drove off resulting in my insurance company having to pay to fix my car. The police did tell me about some Federal Paperwork I can file since this is technically Federal Property but I can't remember what these forms were. To make matters worse, the employee must be a member of the Union of this agency and knew I contacted the police because I was contacted by the Union who wanted me to drop my complaint with the local police for the hit and run arguing that this happened on Federal Property and the local police don't have jurisdiction on Federal Property even though this agency contacts the local police whenever they a law enforcement officer. Does the local police department have jurisdiction on Federal Property and if not, which Federal agency can I contact for help? Is it worth my time to contact a Federal Law enforcement agency for help? I don't like the idea that someone can hit my car and drive off then the local security guards who are not Law Enforcement officers can refuse to assist me and refuse to help the local police who were willing to investigate. What federal paperwork was this local police officer referring to that I can file a complaint regarding personal property damaged on federal property by an federal employee? Can the Union step in and protect this employee from facing any legal actions if he/she is caught? I haven't asked my insurance agent but will this hit and run accident raise my insurance rates since this employee most likely will get away with this or he/she may not even have insurance? I never thought having your car hit on Federal Property can be such a big mess! I always thought local police don't have any jurisdiction on Federal Property but this agency calls the local police whenever a crime is committed on their property such as a week ago a bunch of employees had their cars broken into. I also didn't realize the an employee Union can step in and try and bargain with me to drop charges so their employee doesn't get into trouble.